1. Field of the Invention
The present invention relates to a capacitor for a semiconductor device. More particularly, the present invention relates to a capacitor for use in a semiconductor device having an ability to effectively suppress the oxidization of a material for an electrode when forming a thin dielectric layer, a manufacturing method thereof, and an electronic device that employs the capacitor and thus may be highly integrated.
2. Description of the Related Art
The more integrated a memory is, the smaller the size of a unit cell and the smaller the area of a capacitor. Thus, to realize a capacitor having a large electrostatic capacity in a limited area, extensive research into the use of a capacitor dielectric having a large permittivity, e.g., a high-dielectric material, has been conducted.
High-dielectric materials include tantalum oxide (TaO) and strontium titanium oxide (SrTiO3), which have a larger permittivity than low-dielectric materials such as SiO2 and Si3N4. However, despite the use of a high-dielectric material, a three-dimensional capacitor is still required to realize a capacitor having a large capacitance. To this end, an atomic layer deposition (ALD) method is used.
According to the ALD method, a desired metal oxide thin dielectric film is obtained by chemically absorbing an organometallic compound, which is a precursor, on a substrate, and processing the thin film under an oxygen atmosphere. The ALD method is advantageous in that an organic substance included in a precursor can be removed by a strong oxidizer since the precursor and the oxidizer are introduced using time division.
However, if a lower electrode, which is to be formed below a thin dielectric layer when forming an atomic layer, is formed of a material that is prone to oxidization, e.g., ruthenium (Ru), the Ru electrode may be deformed and the thin dielectric layer may deteriorate, as shown in FIG. 1. Therefore, it is difficult to highly integrate the thin dielectric layer.
FIG. 1 illustrates a capacitor in which a thin strontium titanium oxide (SrTiO3) layer is formed on a Ru lower electrode by a conventional O3 atomic layer deposition (ALD) method. Referring to FIG. 1, it is noted that the conventional O3 ALD method causes a protrusion of the Ru lower electrode to be generated in the capacitor.
As shown in FIG. 2, Ru easily changes into RuO2 or RuO4 under an oxygen atmosphere, which causes the deformation of the Ru electrode.